Time crystals are a phase of matter, for which the discrete time symmetry of the driving Hamiltonian is spontaneously broken. The breaking of discrete time symmetry has been observed in several experiments in driven spin systems. Here, we show the observation of a space-time crystal using ultracold atoms, where the periodic structure in both space and time is directly visible in the experimental images. The underlying physics in our superfluid can be described ab initio and allows for a clear identification of the mechanism that causes the spontaneous symmetry breaking. Our results pave the way for the usage of space-time crystals for the discovery of novel nonequilibrium phases of matter.
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http://dx.doi.org/10.1103/PhysRevLett.121.185301 | DOI Listing |
Nature
January 2025
Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA.
Neurons in the hippocampus are correlated with different variables, including space, time, sensory cues, rewards and actions, in which the extent of tuning depends on ongoing task demands. However, it remains uncertain whether such diverse tuning corresponds to distinct functions within the hippocampal network or whether a more generic computation can account for these observations. Here, to disentangle the contribution of externally driven cues versus internal computation, we developed a task in mice in which space, auditory tones, rewards and context were juxtaposed with changing relevance.
View Article and Find Full Text PDFEnviron Monit Assess
January 2025
College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, 266590, Shandong, China.
A comprehensive scientific analysis of temporal and spatial fluctuations of pollutants during the migration of groundwater is essential for precisely predicting their dispersion patterns and promoting rational regional development planning. In this research paper, a field radial dispersion test was conducted in decentralized drinking water sources downstream of the Fu Tuan River basin in Rizhao City, Shandong Province, China (FRSC). Chloride ion (Cl) solution was utilized as a tracer for the experiment.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Buildings and Construction Techniques Engineering, College of Engineering, Al-Mustaqbal University, Hillah, Babylon, 51001, Iraq.
The land use transition plays an important role for terrestrial environmental services, which had a mixed impact of positive and negative on the groundwater and terrestrial water resource. The health of ecological systems and groundwater depends on the mapping and management of land use. The Ganga basin is one of the most densely populated and agriculture-intensive river systems in the South Asia and the world.
View Article and Find Full Text PDFViruses
December 2024
Friedrich-Loeffler-Institut Institute of Epidemiology, Südufer 10, 17493 Greifswald-Insel Riems, Germany.
African swine fever (ASF) emerged in Germany in 2020. A few weeks after the initial occurrence, infected wild boar were detected in Saxony. In this study, data from wild boar surveillance in Saxony were analyzed.
View Article and Find Full Text PDFEntropy (Basel)
November 2024
Terra Quantum AG, Kornhausstrasse 25, 9000 St. Gallen, Switzerland.
We present the Quantum Memory Matrix (QMM) hypothesis, which addresses the longstanding Black Hole Information Paradox rooted in the apparent conflict between Quantum Mechanics (QM) and General Relativity (GR). This paradox raises the question of how information is preserved during black hole formation and evaporation, given that Hawking radiation appears to result in information loss, challenging unitarity in quantum mechanics. The QMM hypothesis proposes that space-time itself acts as a dynamic quantum information reservoir, with quantum imprints encoding information about quantum states and interactions directly into the fabric of space-time at the Planck scale.
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